When Fictional Universes Collide
by TKcloud9
Summary: Allie Barton, a young mutant from the Avengers universe, gets transferred to the Star Trek universe by the Scarlet Witch's powers, and must first convince herself that this is not a Skrull illusion, while Kirk and co. must convince themselves that yes, she really is the daughter of Hawkeye and Black Widow. Read Puppy Love (Avengers) first, to understand. One-shot crossover.


**A/N: Hello! Welcome to Allie's Adventure in the Star Trek Original Series universe! Fluff and more fluff abound. Takes place sometime after Age of Ultron.**

Allie was used to chaos. So used to chaos, that when the big pink wave of energy rolled over the library, she just grabbed her Bucky Bear, dashed under the nearest table, and curled into a ball, protecting her head and spine. Debris fell and crashed around her, and the ceiling caved in. It went dark, the electricity stopped by the destruction.

Allie cautiously shoved at the heaps of plaster and metal surrounding her. None of it moved. She shoved a little harder, and the heap above the desk let out an ominous creak. She settled back under the desk, scared, and waited until all movement stopped. She turned into a tiny corn snake, and slithered her way up the debris. What she saw made her flee back under the desk - aliens and weapons, and devastation for blocks... Better to stay put until someone came to rescue her.

She shifted herself to a smaller human form, to fit under the desk easier, and hugged her toy tightly. She knew about the tracker in the Bucky Bear, and knew it wouldn't be long before they found her. She even managed to fall asleep...

"Got a life sign!" a voice shouted, a little while later, and there was a terrible creaking of metal and thundering of wood and plaster.

Allie woke up, startled, and flinched away from the pair of hands that appeared under the desk.

A pair of golden hazel eyes, warm and friendly, appeared next, as a man crouched down beside her hideout. "Hi," he said quietly, giving her a small smile. "My name is Jim. I'm here to help you."

She frowned at him. He was carrying a night-night gun on his hip and some sort of scanner. "Are you with SHIELD?" she asked cautiously.

"Star Fleet," he said. "I'm a captain. It's okay. You're safe now." He held out a hand.

"Captain, the building will not maintain its current stability for much longer!" a voice called out.

"We'll be out in a minute," Jim called back, and gave Allie a small smile. "What about it? Shall we go find your parents?" His manner was unhurried, friendly, as if they had all the time in the world. And there was something about him that Allie trusted, something hero-ish, like Steve or Thor.

"Yeah," she said finally, and grabbed his hand.

He pulled her out gently from under the desk, made sure to grab Bucky Bear as well, and carried her on his hip out of the wreckage of the building.

She couldn't help staring at the green-skinned, pointed-eared man who was waiting for them outside the rubble. This was definitely a mutant, she decided, so Professor X or Logan must be here somewhere, or he was an alien or something from another realm, and if they were here the Avengers weren't far behind... she relaxed a little bit.

"Captain," the other man acknowledged.

"Mr. Spock," Captain Jim said, nodding. "Anyone else?"

"This young one was the last of the survivors," Mr. Spock replied, giving Allie a kind look.

"All right. Let's get back to the ship."

Mr. Spock nodded, and pulled out a little cell phone. "Spock to Enterprise. Three to beam up."

Allie's grip on Jim's shirt tightened as the three of them _dissolved_ and then _resolved_ somewhere else. She let out a little gasp of surprise. She _knew_ this place.

"Welcome to the Enterprise," Jim told her, smiling at her awestruck look.

"The Enterprise," she echoed. shaking her head. This wasn't real, was it? It couldn't be. The Enterprise was a TV show. So was this Captain Jim and Spock, and-

An older man, with kind blue eyes and a worried scowl, entered the room, already waving around a medical scanner. "Let me see her, Jim."

"This is Dr. McCoy," Jim told Allie as he set her down on the floor. "He's our chief medical officer, the best doctor in the galaxy."

She nodded slowly and let the doctor scan her. That was part of the TV show too. What was going on?

"Well there's nothing wrong with you," McCoy decided. "You just need a shower and a good meal." He smiled at her kindly. "Maybe some ice cream."

"Where's Wanda?" she asked.

"Wanda?" Jim echoed.

"My friend, my babysitter. She was with me."

"We haven't talked to all the people we've rescued yet," Jim said reassuringly.

She shook her head. "You'd know. She's, she's the Scarlet Witch. You'd have seen her fighting the Skrull."

"The Skrull?" Spock asked.

"The ones that attacked New York," she said. "Where we just were."

The three men shared a worried glance. "Sweetheart, we found you on Denev IV," Jim said. "The colony just suffered an earthquake. We pulled you out of the rubble."

Allie shook her head vehemently. "No, no, I was in New York with Wanda and Sam, and

then Sam got a call from Steve, and he told us there was a Skrull invasion, and then Sam and Wanda went to suit up and told me stay put and I did and then the building started coming down and there was this wave of pink energy and I got under the desk and-"

McCoy put his hands on her shoulders. "Breathe, little darlin'," he said gently. "C'mon, take a deep breath. We'll figure it out, okay?"

She took a shallow breath, fighting the pounding in her chest, and took another breath. Then something occurred to her. What if these were Skrull, their forms pulled out of her memories of the TV show?

All three men were surprised when she suddenly tore away from them and pressed her back to the wall, frowning at them anxiously. "Who are you?" she demanded. "Are you really from Star Fleet or are you aliens?"

They shared a glance. "Miss," Jim said patiently, "we really are from Star Fleet. No one here is going to hurt you. Whatever is going on we will find an explanation for it, I promise. Can you tell us your name, so we can find your babysitter?"

Allie shook her head, terrified. There was no way she was telling any stranger anything about herself or her family. She made her decision, and shifted into a sleek black cat. Before any of the startled grown-ups could move, she bolted for the door and into the grey corridor.

She ran, switching forms every few doorways so they couldn't track her, and ended up in what looked like a game room. No one was in it, and she shifted back into human form, crouching behind a computer console.

Allie leaned against the computer, panting. This ship, or compound, or whatever, was _huge_ , and she was already tired. She let her head fall against the console, and _stared_ at the window in front of her.

Space, outer space, was outside. She jumped to her feet and approached the impossible view. The window felt icy cold to the touch, and she pressed her nose to the glass, looking for a planet.

The planet came into sight a moment later as she craned her head, and she gasped. The planet was bright green and orange. No blue in sight. That was not Earth. She really was somewhere else...

Allie swallowed the urge to cry. Crying was for when everything was over. Right now, she had to figure out what was going on, and there was no JARVIS, no FRIDAY, no Avengers to help her.

She went back to the computer console and tapped on the corner of the screen. It lit up with a menu in a language she didn't recognize.

Allie let out a little sob of frustration and scrubbed at her eyes. "English, please," she begged, kicking the console. "They were speaking English, why can't you be in English?"

"Command not recognized," the computer informed her crisply, in perfect English.

She froze hopefully. "Computer, change user language to English," she said, in her best Tony impersonation.

The menu shimmered and switched to English. It was a menu of games and simulations. That was no use.

"Computer, show me ship's main menu," she said.

"Voice authorization not recognized."

Allie bit her lip guiltily. Mommy had told her never to do it unless it was emergency... this was an emergency. She concentrated, and shifted her vocal cords. "Computer, show me ship's main menu," she said, in a perfect mimicry of Captain Jim's voice.

The menu switched to something a little more professional. USS ENTERPRISE NCC 1701 was emblazoned across the top, and there were screens for the ship's schedule, mission log, and general access.

She pulled up crew manifest, and skimmed through the pictures. There was Captain Jim Kirk, Mr. Spock, Dr. McCoy, Mr. Scott, Lt. Uhura, Mr. Sulu, Mr. Chekov, Chief Kyle, all the ones she recognized from the episodes and lots more. This had to be real.

She pulled up a general specifications report. Maybe if she recognized some of the technology... but warp engines, impulse control, deflector shields, and photon torpedoes were completely unknown to her. This wasn't anything like the arc reactor or nuclear fusion.

Allie tried one last thing, just to make sure they were telling the truth. She pulled up the current mission status from the homepage. "Relief efforts on Denev IV, waiting for relief ships _Saratoga_ and _Nightingale_ ," she read aloud. They were telling the truth.

So how did she get from Earth, New York, to space, Deneb IV?

Allie sighed and rubbed at her eyes again. "Computer, location of Captain Kirk," she asked in Kirk's voice.

"Captain Kirk is on the bridge."

Allie turned off the computer console, and turned into a cat again. This was easier. She made her way to the bridge, after pretending to be Kirk's voice a couple more times.

The funny elevator dumped her onto the bridge, and she shifted into her normal form. "I believe you," she announced to the people, making everyone whirl and stare at her. "I'm sorry I ran away. I just had to check, something." She scratched awkwardly at her dirty sleeve. "Sorry," she said again.

They were all still staring at her. "You are a shapeshifter," Mr. Spock said.

"Yeah. I'm a mutant. Daddy says I can be a X-Men when I'm older." She twisted her hands anxiously. "Can I, can I have my bear? And, um, a snack maybe?"

Kirk smiled and knelt to hand her Bucky Bear.

She took it with a whispered 'thank you', and wrapped her arms around it. "We need to talk," she told the captain firmly. "Like serious grown-ups."

He bit back a smile. "Yes, I think we do. What about?"

"I'm in the wrong universe," she replied. "This is Star Trek. I need to be in the universe with the Avengers. That's my family."

His expression turned a little sad and he exchanged a look with Spock. "All right," he said, "but we really need your name for our search."

"Allie Barton-Romanoff," she said. "My dad is Clint Barton and my mom is Natasha Romanoff, and my babysitter is Wanda Maximoff, and Sam my other babysitter is Samuel Wilson."

"All right Allie," Kirk said gently. "How about we go down to sickbay to see Dr. McCoy, make sure you're not hurt, and then you can get a shower and a snack, okay?" He looked at Lt. Uhura. "Lt, would you come with us?"

"Yes sir." Uhura came over and smiled. "My name is Nyota, Allie. It's very nice to meet you."

"You too," Allie said politely. She took the captain's hand, and they got back in the elevator. She didn't miss the funny glance that Spock gave her. "Why are you all looking at me funny?" she asked.

The captain and Uhura exchanged a glance. "We've never met a shapeshifter before," Kirk said after a second.

"Oh. You don't have X-gene mutants in this universe?"

"Not really."

"Hm. That's boring. What do you have instead?"

"Aliens," Kirk replied.

"Oh. We have those too, just, farther away. But this is the future, right? The twenty-fourth century?"

"Twenty-third," Uhura corrected.

Allie nodded and giggled. "Right, right, sorry. Twenty-fourth is the captain that's bald, and the android that's not as good as Vision. I like him though, he's funny."

Another mysterious glance between adults. "How do you know about the future, sweetheart?" Uhura asked.

"You're on a TV show," came the frank reply.

"A TV show?" Kirk echoed.

"Yep." She bounced on her toes as the lift stopped, and followed them out. "This is a cool ship in real life. Prettier than the helicarriers."

"Thank you," Kirk said, giving her a crooked grin.

They got to sickbay, and McCoy gave her a light scolding about scaring people by running off. Then he gave her a blue lollipop and ran some scans, and had nice Nurse Chapel give her a shower, and a little slot popped out some clothes that were just Allie's size. She got dressed, tugging on the shirt to make it go over her head, and padded back on sock feet to where Kirk, McCoy, and Uhura were standing.

"-I've never seen a biology like hers," McCoy was saying, waving his hands around urgently. "She's got _fluid_ DNA. _Fluid DNA_ , Jim! She's got a whole other pair of chromosome that shouldn't even exist!"

"What about her memories?" the captain asked, frowning. "She's claiming that her parents are Hawkeye and the Black Widow, and her name isn't showing up anywhere on Star Fleet or Federation records."

"I know. How long was she trapped in the rubble for?" McCoy asked grimly.

"Spock says it was about seven hours."

"Enough time to make up an entire story about superheroes," McCoy said, nodding. "She's probably deeply traumatized by the earthquake, and invented a whole new identity to cope-"

"That's not true!" Allie cried, interrupting her eavesdropping. "That's not true! I'm not lying! This isn't a _game_! I didn't make anything up! Lying is bad!" She started to cry against her own will, tired and hungry and needing her parents. "I just wanna go home," she sobbed.

Uhura scooped her up quickly, and rubbed her back. "I know, sugar," she said soothingly. "I know, it's confusing right now."

"No, it's not confusing at _all_ ," Allie sniffled, nestling into the comforting presence anyway. "I _was_ on Earth, there _was_ an attack by the Skrull, it's _true_." She rubbed at her eyes. "But they're looking for me. Tony's gonna find me. Or Heimdall. He sees _everything_. They'll find me, I know it."

Uhura rocked her back and forth, rubbing her back. "Okay," she said, "that's one thing we can believe. Your parents are looking for you."

Kirk laid a gentle hand on Allie's shoulder. "I want to believe you," he said, giving her a look that was almost exactly like Steve's that it made her want to start crying again. "I want to believe you," he said again, "but we need some sort of proof."

"Me," she sniffed. "Didn'tcha see the X-gene? That extra chromosome? Nobody in this universe's got that."

"That is true," McCoy admitted.

"And, and-" Allie caught sight of her Bucky Bear and pointed. "Bucky. He's got a tracker in him, that Coulson put cuz he's a collectible, and it's got a tracer in it from Tony too just in case SHIELD locked us out, and, oh, and it's gotta have DNA or something on it, right? That'll tell you who picked it up and stuff? And it's gotta have energy traces on it, because Wanda was playing with me before the attack!" She beamed at them. "It'll tell you I'm telling the truth!"

Kirk picked up the much-loved bear. "All right," he said. "I'll get this to Mr. Spock and we'll run some tests," he said.

"Okay. But don't rip him open all mean-like. You have to be nice to him. He's a collectible."

Kirk smiled. "We'll be very nice to him, I promise."

She nodded. "Good."

Uhura touched Allie's necklace. "This is a pretty necklace," she said. "It looks African."

"It's from Wakanda," Allie said proudly, lifting up the pendant. Her eyes widened. "This is vibranium. You can check it too. I bet you don't have vibranium here." She pulled the necklace over her head and handed it to Kirk. "Except don't break it either, because the King gave it to me and he'd probably be mad if it broke."

Kirk gave her a solemn nod, and left sickbay.

Uhura smoothed Allie's hair. "Would you like some lunch, little one?" she asked.

Allie's stomach growled in reply, and she blushed. "Yes please," she murmured into Uhura's shoulder.

"Make sure she gets a balanced meal," McCoy called as the two of them left. "No junk food!"

Uhura took Allie to the mess hall, and they had a balanced meal of peanut butter and jelly sandwiches and carrots with ranch dip. And juice, of course. "So, what do you like to do?" Uhura asked her.

Allie shrugged. "I like school. And I like watching movies. And sciencing with Tony and Bruce. And reading stories with Steve and Bucky cuz they do the funny voices. And dancing ballet with my mom. And playing archer with my dad. And lots of things, I guess." She looked at Uhura contemplatively. "How many languages do you speak?"

"Forty-two."

"Cool."

"How many languages do you speak?" Uhura asked the little girl.

"Three. English, Russian, and science!" She giggled into her juice. "That's what Coulson says, anyway."

Uhura smiled at her. "Who's Coulson?"

"He's the head of SHIELD."

"Ah."

Allie frowned at her. "You don't believe me, do you?"

"It is kind of hard to believe," Uhura admitted.

Allie huffed. "Yeah, well, an hour ago you were a TV person, so yeah."

"Oh really?"

"Yup."

The comm clicked on. "Lt. Uhura and Miss Allie to Science Lab 2," Spock's voice announced.

"That's us," Uhura said, standing up.

Allie took her hand. "Let's go!" She urged Uhura down the corridor happily.

Spock and Kirk were waiting for them. "You were right," Kirk said sincerely, kneeling and handing her the bear. "You aren't from this universe. I'm sorry for not believing you."

She hugged him. "That's okay. Sometimes it's diff-cult."

He hugged her.

"What did you find?" Lt. Uhura asked.

"Radiation similar to whenever we deal with dimensional fractures," Spock started, clasping his hands behind his back. "Telekinetic energy similar to those the Platonians used, yet more powerful. Two separate trackers, both with configurations not in our databanks, and dust from concrete with ingredients that date back to the 21st century."

"Toldcha," Allie said happily. "The building fell on us."

They shared a glance. "Do buildings fall on you a lot?" Kirk asked.

"Not on me. On everybody else." Allie sighed. "It's just that the confewence everyone had to go to for extra-terrestrial ambassador-ital stuff, was in the Tower, so I had to leave the Tower, because security. And then the Skrull attacked." She looked at them expectantly. "So, what do we do now?" She yawned. "You got a portal?" she asked, and yawned again. "Portals are easy. Dr. Reed, he's got lots. You got a Dr. Reed in this universe?"

Kirk stifled a grin. "Unfortunately, we don't have a Dr. Reed Richards, but we do have some ideas about portals."

She yawned again. "Cool."

"How about, we go back to sickbay, and you can take a nap?" Uhura asked.

Allie shook her head. "I don't like it in there, it's too hospital-y. I don't like hospitals." She gave them puppy eyes. "Can I stay with you on the bridge?"

"Well," Kirk started.

She turned into a fluffy puppy and gave him real puppy eyes, placing her little paws on his boot pleadingly.

"Are you gonna stay like that and nap?" Kirk asked, amused.

An emphatic headshake yes and a tail wag.

He picked her up and she nestled into his arms. "You're very cute," he told her. "Probably too cute."

The puppy licked his wrist consolingly.

Kirk grinned at her and the three officers headed back up to the bridge. Kirk sat down in his captain's chair and settled Allie on his lap. She rested her head on her paws, and closed her eyes. He accepted a data pad from the yeoman, and started doing paperwork.

Twenty minutes later, the puppy shifted into a soft grey kitten.

"Wow," Sulu said quietly, having just turned around to talk to the captain. "She's incredibly cute."

Kirk grinned.

Allie woke up a few hours later, in a different lap. She yawned, her little feets stretching, and then turned around. She sat up, and looked at Spock's face.

He looked down at her. "Are you well rested, young one?" he asked.

She nodded delicately. She curled up again and nudged her head under his hand.

He smoothed a hand over her soft ears and continued working.

She leaped down to the ground after a few minutes, and scratched her ears. She transformed back into her human form and tied her hair into a little ponytail. She waited patiently until Spock raised an eyebrow at her, and then asked, "Has you made a portal yet?"

"Not yet," he replied evenly.

She played with the zipper on her sweater. "That's okay," she said confidently. "You're the smartest person in this universe so you'll figure it out."

Spock raised an eyebrow at her. "There is no way to measure that."

"Yeah there _is_ ," she said, hanging on the arm of his chair. "You're the Science Officer of the _Enterprise_ , which means you're awesome. And you're a Vulcan, so that's awesome-er. Vulcans are my favorites."

People started hiding their grins behind sleeves.

"And, Tony thinks you're awesome, and Bruce thinks you're awesome, so, you have to be as smart as them, and they're the smartest ever, and so you're probably in the top four. Actually, Steve is really smart too, so, top five."

"Tony Stark and Bruce Banner," Spock elaborated.

"Yep!"

"Fascinating," he said.

She giggled. "Dat's your catchphrase."

"Is it?"

"Yep."

There was a sudden beeping sound from the console. Spock was immediately focused on the console, and Allie retreated two steps to let him concentrate.

"Mr. Spock?" Kirk asked.

"The sensors showed a spacetime disturbance, but only for a moment," Spock reported, straightening up. "It has disappeared."

Allie frowned. "You think maybe it was my universe?"

"Perhaps, young one."

She nodded. "We just have to wait. The multiverse is really..." she frowned. "Really..."

"Really?" Kirk prompted with a smile.

"Vast," Allie decided. "That's a good word. It's really vast. We just have to be patient." She hugged Bucky Bear to her chest. "Captain Jim, do you have any books?"

Kirk handed her the PADD. "Well, there's some on here, but I don't know what you like to read."

She scrolled through the list. "Oh, you've got Anne of Green Gables. That's good." She picked it, and sat on the edge of the raised level, leaning against the rail. "Thank you," she added as an afterthought.

"No problem," he said, amused.

Uhura cleared her throat, and he walked over to her. "Yes, Lt?"

"Where is Allie going to sleep, sir?"

"Good question." He raised an eyebrow at her. "You wouldn't want to handle that, would you?"

She smirked. "I live to serve."

"Lt, you're an angel."

"Yes captain." She went over to Allie. "Allie, sweetheart, for tonight you're going to bunk with me, okay?"

"Like a sleepover?"

"Exactly like that."

"Awesome." She smiled complacently at the whole universe in general as she read.

They were all smiling (even Spock) a half hour later when Allie nodded off, still holding firmly to the PADD.

Kirk knelt down to pick her up. "Time for bed," he said gently.

She buried her face in his shoulder. "'M not tired," she protested.

"I think you are."

"Nuh-uh." She sighed, completely asleep.

Sulu grinned. "She is too cute."

Kirk grinned and nodded to the turbolift. "All right, Lt, lead the way."

Uhura went ahead of Kirk into her quarters and made up the sofa with some extra blankets provided by the quartermaster. Quartermaster Rawlins had a daughter himself, and he provided a little flower-and-spaceship patterned blanket.

Allie didn't even stir as she was tucked into the blankets. She just snuggled into the sofa and gave a sleepy sigh.

Kirk grinned. "Night, Lt. We'll comm you if there's an update."

"Thank you, captain."

Off-duty for the rest of the night, Uhura changed into her pajamas, and settled down in her bed with the latest Communication Journal.

It was 0100 that Uhura was woken up by a small tug on the blanket.

"Lt. Uhuwa?" came a tiny whisper. "The ship's breathin' and it's really dark and it's scary."

She peered blearily at the five-year-old. "You want to come cuddle with me, sugar?" Uhura asked.

"Yes please." Allie climbed in bed with her and wrapped a little arm around her neck. "Night night."

"Night night," she replied, amused.

Allie fell asleep less than a minute later.

When Uhura woke up at 0700 the next morning, she had a small puppy nestled on her stomach, the little white head resting on little black paws. She smiled and moved Allie to the side as she got up. Before she was ready for the day, Allie stretched, yawned, turned into a little girl, and woke up. "Morning?" she murmured.

Uhura smiled. "Good morning," she said, smoothing Allie's hair. "Sleep better?"

"Yep, had a weird dream though," Allie mumbled, eyes still closed. "I was on the Enterprise, and met Kirk, and Spock, and-" She opened her eyes, and stared at the different ceiling. "Wait..." She rolled over to look at Uhura, her smile falling. "I'm not home?" she asked.

Uhura shook her head. "We're still working on it, darling. I'm sorry. You'll just have to be a little more patient, okay?"

Allie curled into the flower blankie and ducked her head, and scrubbed at her eyes with a fist. "Okay," she said brokenly. "I can be patient. I waited four whole days for Tony to come out of his lab to watch the new Disney movie with me."

Uhura picked her up and kissed her forehead. "You're a brave girl," she told her. "How about some strawberry crepes for breakfast?"

"Okay."

Allie was given a little pair of leggings and a colorful soft tunic from the replicator, and Uhura braided her hair with a cheerful yellow ribbon. They skipped their way to the mess hall, and had strawberry crepes with Chekov, Sulu, and Scotty.

Allie was fascinated by Mr. Chekov's accent. It was just like in the TV show. Even mommy didn't have an accent like his, not even when she was super tired. "Was everything really invented in Russia in your universe?" she asked.

"Yes," he said firmly.

"Woooowww," she said, eyes wide as saucers.

The other three exchanged a glance and rolled their eyes.

"What do you say if we spend the morning in the botany lab, Allie?" Sulu asked. "I've got some Xanthian lilies that need some TLC, and I think between you and me we could handle it."

"I've never seen an alien plant," Allie said interestedly.

The others grinned as she followed Sulu out of the mess hall, asking, "What do they look like? Have you got any talking plants? Is there a giant Venus fly trap like in Journey to the Center of the Earth?"

Allie spent the morning with Sulu, had lunch with Captain Kirk, and spent the afternoon with Spock running experiments. She noticed him staring at her. "Whatsamatter?" she asked.

"You have thus far shapeshifted into three animals," he said, "all of the canine and feline species. If I may ask, what other forms can you take?"

She smiled. "Want me to show you?"

He raised an eyebrow. "I would be honored."

She turned into a bird, a dragon, a snake, a cat, a dog, a calla lily, and a Xanthian lily, a Frost Giant, and a Lego, for giggles. Then, she looked at Spock for a long moment, and shifted into a little Vulcan. "Is this right?" she asked.

Spock could not repress an almost-smile. "You are a perfect copy of a Vulcan," he said.

She frowned. "Then I did it wrong."

"In what way?" he asked.

"I wanted to be a half-Vulcan," she said cheerfully. "Like you." She concentrated, and raised a single pointed eyebrow. "Fascinating," she intoned in a deep voice.

"Aww," said a voice from behind. It was Captain Kirk, and he was absolutely beaming at them. "You have a perfect mini-me."

Allie shifted into her regular form and hugged him tightly around the waist. "Hi."

"Hello."

"How is space doing?" she asked solemnly.

Kirk grinned. "Space is doing very well."

"Good. And, how are you?"

"I'm fine too."

"That's good." She hugged him tighter. "Can we eat now? Shapeshifting makes me hungry."

He chuckled. "Sure."

They had linguini with white sauce, and Kirk sneaked a piece of pie for Allie past McCoy's watchful gaze. She graciously shared it with him.

The evening was spent with Chekov, speaking in Russian and playing checkers.

The next day Allie was seriously missing her family. She didn't want to eat, she didn't want to play. All she wanted was her mom, or dad, or Steve, or Bruce, or Tony, or Thor, or the twins, or _anyone_ from her universe, and she was trying so hard to be brave and not cry...

Spock looked up at the little sniff coming from the corner of the lab. "Allie?" he asked.

"M not cwyin'," she muttered, wiping at a rebellious tear that trailed down her cheek. "'M not." Another tear trickled down her other cheek and she sniffled.

Spock repressed a feeling of panic. He'd never dealt with crying children - that was the province of Doctor McCoy or the captain. "You must not lose hope," he said gently, coming over to kneel in front of her.

She let out a sob and curled into a miserable little ball. "I want my _daddyyyyyy_ ," she said sadly, losing the last word in a sob.

Spock bit the bullet, and did what any human would have done confronted with a crying child - he picked her up and held her close, accepting the vibrant ball of emotions that came with her. Fear and loss overwhelmed him, and he could feel the yearning for parents and family. He brushed the hair back from Allie's face, and caught a brief glimpse of a man and a woman with kind smiles and loving eyes. "Shh," he said gently but firmly, "you must not give up, Allie. Either we will find your universe or they will find us."

"You promise?" Allie sniffled.

"I promise," he said, and he meant it.

"Vulcans don't lie."

"No, we do not."

"Good." She let a few more tears out, and sighed. "You has good hugs," she murmured, after a moment. "Almost as good as Thor."

He patted her back a few times, and stood up to bring her to his workstation. He froze in his tracks as he saw Kirk standing there, smiling like he'd just seen the cutest thing ever. "Captain," he said stiffly.

"Spock," Kirk said, grinning at him. He walked over and put a gentle hand on Allie's back. "I came to see if our favorite guest wanted to have some lunch."

Allie wrapped an arm around Spock's neck. "No thank you," she said. "I'm not hungry."

"Are you sure?" Kirk asked gently. "What if Spock came and ate with us?"

"A nutritious meal is logical," Spock told the five-year-old.

She nodded. "Pizza?"

"Pizza," Kirk agreed.

"Doctor Bones?" Allie asked, barely lifting her head from the 3D model of a caffeine molecule, made from tongue depressors and plasticine.

He repressed a grin. "Just Bones, darlin', or Doctor."

"Okay, Doctor Bones," she said absently. "How old is your daughter?"

He looked up, startled. "How did you know I have a daughter?"

"You mention her in the show," Allie said. "Is she really pretty?"

His gaze softened. "Yes, she is. She's beautiful. And she's 27 years old."

"Where is she?"

"On Earth, studying to be a xenobiologist."

Allie smiled. "She's gonna be a doctor like you?"

"Yup. What are you going to be when you grow up?"

She smiled. "A superhero like daddy and mommy and Steve and Tony and Bruce and everyone."

"That sounds pretty dangerous."

"Yup. But someone's gotta save people." She smiled up at Bones.

Bones frowned. "Is that what your mom and dad tell you?" he asked, trying to keep his tone casual.

Allie shook her head. "Nope. I can be whatever I want to be, even if I decide to be a calla lilly forever'n'ever. Dad said so." She shrugged. "I might be an engineer or a scientist or something instead, but I don't know. I'm only little you know, Doctor Bones."

He kissed her forehead. "Yes, you are."

She leaned back into his arms with a happy sigh. "You've got a nice hug, too," she decided. "Everyone on this ship gives good hugs. Captain Jim, Mr. Spock, Nyota too..."

Bones nearly dropped his PADD. "Spock?" he inquired, trying desperately for nonchalant.

She nodded, completely oblivious to his rising glee. "Uh-huh. Really good hugs."

"Oh really," Bones said, suppressing a maniacal cackle. "And when was this?"

"Yesterday in the lab." She looked up at him curiously. "Why?"

He squeezed her close. "No reason. Is it your naptime, darlin'?"

She yawned. "Nah."

"Nah?" he echoed, grinning. "Well, why don't you read until it is?"

"Okay." She made no move to get up from his lap.

He raised an eyebrow. "Do you want down?"

"No I'm good," she replied, snuggling into his shoulder and closing her eyes. "I think it is naptime, Doctor Bones."

He kissed her forehead again. "All right, sweet pea, you take a nap."

"Yup." She was asleep within minutes, her little face tucked into his neck as she slumbered.

Bones' mind went back to happy memories of holding his own little girl as she napped, and slowly his attention drifted away from quarterly reports to memory lane, and from there to the land of Nod...

Cmdr. Spock was the third member of the crew to find Doctor McCoy and Allie napping peacefully in the doctor's office. The first two, Nurses Chapel and D'Arnot, had been incapacitated by fond cooing over the tableaux and retreated to the storage room to giggle. Spock did not giggle, although his eyebrow did rise imperceptibly, and the corners of his mouth softened. He stepped outside the office and pressed the wall comm. "Captain Kirk to sickbay," he paged.

"On my way."

The captain arrived at Sickbay with a worried frown on his face. "What's up?" he asked his first officer.

Spock gestured wordlessly into the CMO's office.

Kirk took one look at that, and melted. "Aww," he cooed, "they're so cuuuute..." He tapped Spock on the shoulder. "Go find a camera. I want this immortalized for the next time Bones tries to pretend he's heartless."

Spock would not refuse an order from his captain. He also had a sudden urge to immortalize this moment. He found a camera in the storage room, ignoring the smirks from the nurses, and gave it to Kirk.

 _Click_. It was perfect. It was a postcard moment. It was-

Blue eyes snapped open. "What in the Sam Hill!?" McCoy hissed.

Kirk smiled innocently. "Nice nap, Doctor?" he asked.

Bones started to scowl. "I was not _napping_ ," he said icily.

"Uh-huh," Kirk said dryly.

Allie woke up from the sound of voices, and blinked lazily. "You 'wake now?" she asked, still drowsy. "I woked up a while ago but you were 'sleep so I went back to sleep, can we have French fries?" She stared, wide-eyed, as the gallant starship captain burst into laughter, and the irascible doctor blushed. "What's so funny?" she asked, bewildered.

"Nothing," Bones said, his glare promising retribution. "Nothing at all. Let's go have French fries."

A day later a picture showed up in Spock's inbox, of the half-Vulcan cuddling Allie, her arms around his neck. It was a painfully adorable picture, pulled from the security footage. _Cute, isn't it?_ was the caption.

Spock, in the privacy of his quarters, felt the tips of his ears turn green.

"Computer, locate Captain Kirk."

"Captain Kirk is in Jefferies Tube 12-A, sub-junction C."

A sigh. "Computer, locate Allie Barton."

"Allie Barton is in Jefferies Tube 12-A, sub-junction C."

Another sigh. "Seriously, Jim?"

Nurse Chapel looked over curiously. "Doctor?"

"Nothing, nurse," McCoy said irritably. "Just children being children. Children who forgot their communicators. Children who think it's a good idea to take another _child_ into the bowels of a giant trouble magnet!"

Nurse Chapel grinned and went away.

Spock was waiting for the captain when he finally emerged from the Jefferies Tube two hours later. "Captain," he said impassively.

"Mr. Spock." Kirk reached behind his collar and came away with a small green lizard. "I was taking our young guest on a tour of the ship."

"I see."

The lizard tapped a tiny foot against Kirk's palm.

"Yes, dinner, good plan. Join us, Cmdr?"

The next day, it happened. Allie was at the navigation console with Chekov, learning about three-dimensional star charts, when his panel, and Spock's, began to beep.

Chekov moved her hastily out of the way, and she sat on the step to the upper level as the bridge buzzed with activity. "Sir, I'm reading Cerenkov radiation and- it's a wormhole, sir."

"Forming where?" Kirk asked.

"Here," Chekov said, bewildered. "On the bridge, keptin."

There was suddenly a _hole_ in the air of the bridge, and a bright light.

Four people appeared from the flash of light. It was Captain America, Iron Man, Hawkeye, and Scarlet Witch, in the flesh. "Daddy!" Allie cried, launching herself at Hawkeye with sudden tears. "Daddy!"

He swept her up and held her close, pressing a kiss to her cheek as he closed his eyes against the crash of relief. "Allie," he breathed, choked up. He leaned back a little bit, inspecting her closely. "Are you all right, baby?"

"Yup." She hugged him tightly. "I missed you _so_ much."

Steve looked at Kirk, and Tony looked at Spock.

"Captain," Steve said politely.

"Captain," Kirk replied, equally respectful.

"Is that a self-contained fission device?" Spock asked, nodding to the arc reactor.

"Yup."

"Fascinating."

Tony smirked. "Thanks."

Allie tugged at Clint's shirt. "Daddy, this is Star Trek. How did you find me?"

"With lots of hard work," Tony answered instead. He glanced at a readout on his wrist. "Uh, we've got twenty minutes before we can go back." He looked at Kirk. "How about a tour, captain?"

"Since we've got time," Kirk replied easily. "Mr. Sulu, you have the conn." He and Spock ushered them into the lift.

Spock gave the tour, mostly, and Kirk chimed in with anecdotes about missions. McCoy joined them at one point, and was wondering if he could discretely take a scan of Wanda Maximoff's brain.

She gave him a knowing smirk.

Allie completely spaced out, happy in the security of her father's arms, until the twenty minutes were up and the portal was ready to go. Then she wriggled out of her dad's arms and went up to Captain Kirk.

He knelt to her level, and she hugged him tightly. "Thank you for helping me," she said, and kissed his cheek.

He kissed her forehead. "I am very glad to have met you," he told her.

She went up to Spock next, and offered him the Vulcan salute. "Live long and pwosper," she said solemnly.

He surprised everyone by kneeling and drawing her into a hug. "Peace and long life, young one," he said, returning the gesture.

She smiled at him, and then turned to Bones.

He grabbed her in a hug, and said, "Now be good for your parents, okay?"

"Okay, Doc Bones."

She hugged Uhura, too, and then it was time to go, so she waved at Sulu, Chekov, and Scotty. "Stay safe!" she told all of them, as Clint picked her up.

"You too," Kirk replied, and looked at Clint. "You've got an amazing kid, Mr. Barton."

He grinned proudly. "Yes, I do."

The portal activated, and they were gone.

Allie was hugged half to death by the rest of the Avengers when she got back, and Bruce told her that she was the first person in recorded history to have traveled to a supposedly-fictional universe. Tony gave her a small silver plaque to put in her room, with a picture of the Enterprise engraved into it.

Allie treasured her memories of that other universe and the kind people in it, for as long as she lived.

 **A/N 2: Thanks for reading!**


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